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Flow Induced Sympathetic Vibration in Control Valves.

Flow Induced Sympathetic Vibration in Control Valves. Asher Glaun P.E. Dresser-Masoneilan Valve World 2010. Background. Control valves on compressor anti-surge and other gas applications are prone to mechanical vibration. Flow-to-Open required for low noise

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Flow Induced Sympathetic Vibration in Control Valves.

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  1. Flow Induced Sympathetic Vibration in Control Valves. Asher Glaun P.E. Dresser-Masoneilan Valve World 2010 Valve World 2010

  2. Background • Control valves on compressor anti-surge and other gas applications are prone to mechanical vibration. • Flow-to-Open required for low noise • Compressible fluids with high mass flow rates drop large amounts of energy across the valve imparting some of this energy to the valve trim components. • Plug rotation is one of the possible consequences. Valve World 2010

  3. Sources of mechanical vibration in valves • Internally generated fluid excitation • Upstream generated excitation • Pipeline resonance • Support structure compliance • Acoustic induced vibration • Mechanical looseness Valve World 2010

  4. Internally generated fluid excitation • Large changes in direction create areas of high acceleration and low pressure cells that form adjacent to the valve wall. Valve World 2010

  5. Internally generated fluid excitation • Under the right conditions, low pressure cells can form and detach from the valve wall. • Vortex shedding is periodic in nature. Fluent LES transient analysis Valve World 2010

  6. Internally generated fluid excitationVortex Shedding Valve World 2010

  7. Internally generated fluid excitationVortex Shedding Fluent LES Model. Time Step: <0.001 sec Valve World 2010

  8. Vibration mechanism • Vortex shedding created by high velocity flows around sharp bends in valves. • Periodic pressure pulsations interact with valve trim. How does this affect the valve? Valve World 2010

  9. Natural frequency resonance of plug-stem system Valve World 2010

  10. Valve plug–stem assemblies • Independent of forcing magnitude • Once stared, very difficult to contain • Sensitive to plug mass and stem diameter Valve World 2010

  11. Abatement Strategies • Plug tip shape to neutralize fluid forces • Reduced aspect ratio • Pressure pulses prevented from travelling into the plug cavity • Less pressure asymmetry • Less vortex shedding Valve World 2010

  12. Abatement Strategies • Correct valve sizing • Valve size • Valve seat Mach number • Valve noise • Flow direction • Inlet velocity • Inlet flow profile • Upstream piping (reducers) Valve World 2010

  13. Abatement Strategies • Natural Frequency • Increased Plug stem stiffness (diameter, length) • Decreased plug mass • System damping • Plug to cage clearance • Plug/cage clearance flow Valve World 2010

  14. Vibration ExampleProblem solved with plug/stem geometry changes only Valve World 2010

  15. Conclusion • Careful attention to proper valve sizing and design based on understanding the fluid phenomena inside the valve can lead to consistent and trouble free valve operation in severe service applications. Valve World 2010

  16. Bibliography • White, Frank (1974), “Viscous Fluid Flow”, 3rd Edition. McGraw-Hill, N.Y. • Meorovitch, Leonard (1975), “Elements of Vibration Analysis”, 2nd Edition. McGraw- • Hill, N.Y. • Roth, Kurt W (1999) “The impact of stroke length upon low-frequency valve upstream • pressure pulsations”, “Proc. of 1999 ASME/JSME FluidsEng. Div. Summer Meeting.” • ASME. • Reismann, H & P. Pawlik, (1991) “Elasticity, Theory and Applications”, Krieger, Florida • Saad, Michael (1985) “Compressible Fluid Flow”, Prentice-Hall, N.J. • Shigley, Joseph (1977) “Mechanical Engineering Design” 3rd Edition. McGraw-Hill, • N.Y. • Boresi, A & R. Schmidt & O Sidebottom (1993) “Advanced Mechanics of Materials” 5th • Edition. John Wiley & Sons. • O’Keefe, William (1987) “Powerplant valves: Special Report” Power Magazine” • Coffman, J.T & Bernstein, M.D. “Failure of Safety Valves Due To Flow Induced • Vibration”, “Flow Induced Vibrations – 3rd Nat. Congress on Pressure Vessel and • Piping Tech.” ASME, N.Y. • Morse, Philip M. & Ingard, K. Uno (1968) “ Theoretical Acoustics” McGraw-Hill, N.Y. • ASME (2008) “Power Piping”, “ANSI/ASME B31.1 2007 App. II” Valve World 2010

  17. Thank You Valve World 2010

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